This invention relates to microscope objectives and more particularly to infinity corrected microscope objectives having and N.A. of substantially 0.85.
It is an object of this invention to provide objectives well corrected for all aberrations except lateral chromatic aberration. The residual lateral chromatic aberration between 486.1 nm and 656.3 nm is 1% of the angular magnification at 589.3 nm across usable field.
When used with a telescope lens having an effective focal length (efl) of 183 nm, the objective provides a lateral magnification of substantially 50.times. at 589.3 mm.
U.S. Pat. No. 4,037,934 issued July 26, 1977 relates to a five-component microscope objective having a magnification of 50.times. to 70.times. and an N.A. of 0.95 with longitudinal chromatic aberration corrected to a degree providing a semi-apochromatic objective. The lens components of this objective differ from those of the present invention in that the fourth component is a singlet spaced closely to the fifth component while in the objective of the present invention, the fourth component is a doublet widely spaced from the fifth component. In addition, the first condition considered essential by the reference patentee is not satisfied since the dispersion value of the first lens is less than 45.
U.S. Pat. No. 4,184,747 issued Jan. 22, 1980 is the closest reference to the structure of the present invention and described a five-component microscope objective having a power of 40.times.. The structure of this patented objective differs from that of the present invention in that the third lens component of the reference has a radius greater than O while the structure of the third lens component of the present invention provides a first surface which is plano, i.e. radius equals .infin.. Furthermore, the second lens component of the present invention is a bi-convex singlet instead of a concavo-convex singlet required by the reference. In addition, the structure of the present invention does not satisfy the seven requirements of the reference defined as necessary to obtain a flat image field and good aberration correction.